Portland Fire Bureau estimated more than 70,000 people gathered in Waterfront Park to hear Obama speak.

EUGENE, Oregon (AP) -- After sharpening his attacks on Republican John McCain, Barack Obama is ready to lay a symbolic claim to the U.S. Democratic presidential nomination following Tuesday's round of primaries. The upcoming primaries in Oregon and Kentucky should leave Obama less than 100 delegates away from reaching the total 2,026 needed to secure his party's nomination after an epic battle with Hillary Rodham Clinton. Obama was campaigning over the weekend in Oregon, where polls say he has a comfortable lead, while Clinton has a strong lead in Kentucky before that state's primary and plans to campaign there through Tuesday. In Portland, a crowd estimated at 70,000 gathered in Waterfront Park to hear Obama speak. At stake are 51 delegates in Kentucky and 52 in Oregon. Obama has built a solid lead in Democratic National Convention delegates over Clinton, and is now working overtime to give an air of inevitability to his campaign for the nomination. In recent days, he has spent more time focusing on his differences with certain Republican nominee McCain than sparring with Clinton. Obama's aides announced that he planned to hold a rally on primary night Tuesday in Iowa, where his solid win in January's leadoff caucuses propelled him to his status as the front-runner. The rally is the latest effort by Obama, who is bidding to become the country's first black president, to shift attention away from the primary season to the November election even though Clinton continues to maintain a full campaign schedule in the remaining primary states. Obama's aides describe Iowa "as a critical general election state that Democrats must win in November." The same can be said for Florida, where he will campaign for the first time this week. Neither Obama nor Clinton campaigned in Florida after the state, along with Michigan, violated Democratic party rules by moving up their primaries to January, earlier than rules allowed. Clinton won both primaries although Obama's name was not on the ballot in Michigan. The party stripped both states of their delegates for the scheduling infraction, and Clinton and Obama have been at odds over seating the delegates at the national convention. During his Oregon campaign swing Saturday, the Illinois senator returned to a debate launched Friday with McCain on foreign policy. U.S. President George W. Bush and McCain suggested Democrats could not be trusted to be tough on terrorists. Obama spoke to about 1,400 people at a town hall meeting in Roseburg, Oregon, arguing that McCain would merely follow a failed policy set by Bush. "If you agree that we've had a great foreign policy over the last eight years, then you should vote for John McCain, you shouldn't vote for me," said Obama. "That's what this debate is all about, that's the choice in this election. Do you want more of the same or do you want change?" McCain spokesman Tucker Bounds argued that Obama's foreign policy shows "incredibly weak judgment. We're a nation rooted in a history of sacrifice and achievement, not in lofty campaign rhetoric or campaign promises." Obama has largely ignored Clinton, while tussling with McCain in a general election-style dispute over foreign policy. Clinton has also adjusted her sights. Instead of criticizing her Democratic opponent, her latest television ads either focus on bread-and-butter economic issues or take aim at the media and political pundits who are counting her out. Clinton, whose hopes are fading to become the first female U.S. president, has insisted she is staying in the race until the last primaries on June 3 in Montana and South Dakota. "There are some people who have been saying for months that this is over, and every time they say it, the voters come back and say, 'Oh no it's not, we're not ready for it to be over,"' Clinton told supporters Saturday as she stood on a stage in front of a stack of whiskey barrels at the famous Maker's Mark distillery in Loretto, Kentucky. "You don't quit on people and you don't quit until you finish what you started, and you don't quit on America." Clinton is hoping for a big win in Kentucky, crisscrossing the state whose demographics resemble neighboring West Virginia, which gave her a much-needed victory last week. Both states are overwhelmingly white, rural and have more residents below the poverty line and without college degrees than the national average -- the kind of working-class voters who have helped boost Clinton to victory in other states. But Obama already enjoys a delegate advantage that makes it mathematically unlikely for Clinton to overtake him in the remaining five contests. Her campaign instead hopes to win over the influential party leaders and elected officials known as superdelegates, who are free to vote for any candidate at the party's national convention in August, with the argument that she would be the better Democrat to face McCain in November. But Clinton, who led Obama in superdelegates for most of the year, recently lost that lead. He now leads 295.5 to 274.5 -- including a superdelegate in Maryland he collected Saturday. Since neither candidate is likely to get enough delegates to secure the nomination through the remaining primaries, the superdelegates will most likely determine the outcome. In Nevada on Saturday, Obama stole a delegate from rival Hillary Rodham Clinton by drawing more supporters at the state Democratic convention Saturday. The pickup brings Obama's delegate total to 1,907 to Clinton's 1,718. Clinton began the nomination race far better known than Obama, and was considered by many to be the likely nominee in the early days of the campaign. Obama countered that perception with an intense grass-roots campaign in Iowa that led to a surprising win. Though Clinton rebounded with a win in the New Hampshire primary, Obama has maintained his status as the front-runner. McCain joked that Democrats should not to rush to choose between Clinton and Obama during a guest appearance on the "Weekend Update" satirical news show segment on the TV comedy sketch show "Saturday Night Live." Earlier, the 71-year-old McCain, who would be the oldest person ever elected president, joked about his age as he appeared in a phony campaign ad. "I ask you, what should we be looking for in our next president?" McCain said. "Certainly, someone who is very, very, very old." "I have the courage, the wisdom, the experience and, most importantly, the oldness necessary," McCain said. "The oldness it takes to protect America, to honor her, love her and tell her about what cute things the cat did."